The present invention relates to an operation control apparatus suitably applicable to a working system of a Flexible Manufacturing System (FMS) particularly provided with a number of pallets.
In the prior art, there is provided a working system having a pallet stocker in which a number of pallets are accommodated and a conveying unit such as conveying bogie for automatically conveying the pallets from the pallet stocker to a machining center 1. Such working system, as shown in FIG. 8, is further provided with a control unit 2 consisting of a Macro Processor Unit (MPU) and a Numerical Controlled (NC) section installed in the machining center for controlling the same, another control unit 4 for controlling the operation of the conveying unit 3 such as conveying bogie and a system controller 5 such as host computer connected to both the control units 2 and 4.
In this working system, the controls of inputting of a scheduled data, decision of working order of the pallets and pallet conveyance of the conveying unit 4 are performed.
As the pallet stocker, a loop type of a flat installation arrangement is widely utilized. The conditions or status of the pallets to be accommodated in the pallet stocker of this type are generally displayed through lighting, at the completion of a preparatory operation, of display lamps arranged in a row on a pallet display section provided on a surface of a cathode ray tube (CRT) of a control unit of the machining center and a preparatory board, Further, in an FMS provided with a multi-layered type pallet stocker and a system controller such as host computer, the status or conditions of the pallets are displayed on the system controller. As described above, there is no prior art system which is equipped with a display unit which can independently display only the conditions of the pallets.
However, the following problems have been provided in the operation control apparatus of the conventional working system of the structures described above.
1. The control system has a complicated structure and hence has a long access time. That is, various kinds of data communications are executed between the control unit 2 of the machining center 1 and the system controller 5 and between the control unit for the conveying unit 3 and the system controller 5, and instructions for the conveyance are outputted in response to these data communications, so that signal processing time for function generation is elongated.
2. Much time is required for the maintenance of the working system. For example, when the conveying unit 3 is stopped during the scheduled operation, it is necessary to judge whether the cause of this operation stop is based on the machining center 1, conveying unit 3 or the system controller 5. This judgement requires relatively long time, resulting in the lowering of productivity. Moreover, re-setting of the scheduled data and returning of the respective units or apparatus to the initial states will have to be done after performing a countermeasure against the stopping of the conveying unit 3.
3. It is impossible to execute an interrupt instruction of the pallet. That is, even in a case where an optional pallet is urgently required to be used, such pallet cannot be used during the scheduled operation without interrupting the scheduled operation.
Furthermore, as mentioned above, the conventional working system is not provided with a pallet status display unit independently displaying only the status or condition of the pallet. For this reason, there is a strong desire to develop a pallet status display unit for surely and easily recognizing the status or conditions of the respective pallets from an external portion thereof for the working system in which a number of pallets are accommodated in the pallet stocker in a multiple stage.
For example, when it is required to display the status or conditions of the pallets in the loop-type pallet stocker of flat arrangement type, since the pallet display section is arranged in a row, the recognition or distinction is made difficult in correspondence to the pallet, and the power of visual recognition is not good. Moreover, in order to confirm the pallet condition except the preparation completion, it is necessary to visually confirm the condition in combination of the confirmation of the display on the CRT of the control unit of the machining center located apart from the pallet display section. Still furthermore, since the display on the CRT displays the recognition of the pallet status generally through characters or letters, the recognition is not made easily and clearly, and moreover, such display further includes limits for displaying the numbers of the pallets on one display surface. Thus, accordingly, with respect to a large stocker number of pallets, further search or page turning operation will be required.
In addition, the system controller such as host computer is operated in response to complicated software concerning working scheduled control, working program, tool management, instructions on the conveying unit, instructions on the machining center and the like, and the pallet displaying is also performed by a portion thereof, so that there is lacking in real time operation in auxiliary functions. Moreover, since the system controller is usually installed in the computer apart from the pallet stocker, it is difficult for an operator to instantaneously grasp the matching with an actual object.